Millennials in the US spend nearly 30 hours a month on social apps, 26 of those on Facebook, according to a comScore report. Social media apps account for 29% of overall mobile app use.

US mobile millennials are Facebook’s best friends. That’s one of the more interesting findings in a report released this week by comScore.

The digital measurement firm found that people aged 18–34 spend an average of 26 hours a month — nearly an hour a day — on Facebook’s mobile app. That high usage drove the overall numbers for US mobile users, who spend more of their time on mobile devices on social apps than any other category.

The average mobile user spends nearly 26 hours a month on social media apps. As the chart below shows, that’s 29 percent of the total time spent on mobile apps. The total social media usage share is four percentage points higher than comScore’s figures from last year.

The report focused on overall mobile vs. desktop usage trends and found mobile has taken a 62 percent share, with apps accounting for the large majority of mobile engagement and a small number of apps dominating the market. You can read our analysis of the overall report here.

There’s no more dominant player than Facebook. The social network is the top overall app in users — 125 million in the US, according to comScore — and engagement. Nearly 50 percent of mobile users use Facebook more than any other app, and for almost 80 percent of people, it’s one of the top three most used apps. “With constantly refreshing social content and home screen accessibility for most users, the app is made for habitual usage,” the report said.

Although the comScore report didn’t release overall time-spent figures for Facebook, the social network clearly accounts for the great majority of people’s social app use. Need evidence? Check out those millennial Facebook totals, leaving second-place Instagram and the rest far behind:

While millennials were the most socially plugged-in age group — “social media junkies” in comScore’s terms — their older peers also regularly use social media apps, and use them to a higher degree than entertainment apps, the second most popular category, as this chart shows:

Because millennials are so active — and let’s face it, they are the future — the report studied their behavior in great detail. The chart below shows the apps that have the highest concentration of millennial users, with a large majority being social, chat and music-related.

ComScore looked deeper at Snapchat and found that nearly three of every five people in the younger millennial group (18–24) uses the chat and social entertainment app. Penetration among the 25–35 age group is lower but gaining:

The biggest takeaway for marketers? Pay attention to the young crowd.

“Millennials are the heaviest app users and they spend a lot of time on social media and other platforms,” the report concluded. “Publishers must have a well-developed platform strategy to get mobile traffic and find ways to convert app users.”